[metapost] turningnumber revisited

[luigi scarso]

On Mon, Jun 27, 2011 at 1:03 PM, Boguslaw Jackowski <jacko at bop.com.pl> wrote:
>
> Luigi:
>>
>> Do you have some explicit examples of  paths with strange turning numbers
>> ?
>
> This seems to be ever-recurring problem. :)
>
> If anybody is able to predict the result of the following MF/MP code
> run on MF and MP
>
>  path p;
>  if known mitered: beginfig(100); fi
>  p:=(0,0)..{up}(1,1) & (1,1){down} .. (2,0) -- cycle; show turningnumber p;
>  if known mitered: draw p scaled 100; fi
maybe
from 0 to 1,1 +90°;
then +180° (hence I have 270°)

then from 1,1 to 2,0 +90° (hence I have 360°, i.e. turning number = +1)

then +180° (hence I have 360°+180°)

then from 2,0 to 0,0 go straight

then +180° to match the initial position (hence I have 360°+360°
turning number = +2)


-- 
luigi